U.S. patent number 10,732,447 [Application Number 16/490,909] was granted by the patent office on 2020-08-04 for touch panel and electronic device.
This patent grant is currently assigned to SHARP KABUSHIKI KAISHA. The grantee listed for this patent is Sharp Kabushiki Kaisha. Invention is credited to Hidetsugu Kawamori, Takenori Maruyama, Jean Mugiraneza, Yasuhiro Sugita.
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United States Patent |
10,732,447 |
Maruyama , et al. |
August 4, 2020 |
Touch panel and electronic device
Abstract
The purpose of the present invention is to achieve further
miniaturization and performance improvement in a pressure
detection-type touch panel. The touch panel (1) includes a TP upper
side electrode layer (19) located above a CF substrate (18); and a
TP lower side electrode layer (16) located below the CF substrate
(18) and above a liquid crystal layer (14); an ITO layer (13)
located above the TFT substrate (11) and below the liquid crystal
layer (14); and a piezoelectric element layer (15) located between
the TP lower side electrode layer (16) and the ITO layer (13).
Inventors: |
Maruyama; Takenori (Sakai,
JP), Mugiraneza; Jean (Sakai, JP), Sugita;
Yasuhiro (Sakai, JP), Kawamori; Hidetsugu (Sakai,
JP) |
Applicant: |
Name |
City |
State |
Country |
Type |
Sharp Kabushiki Kaisha |
Sakai, Osaka |
N/A |
JP |
|
|
Assignee: |
SHARP KABUSHIKI KAISHA (Sakai,
JP)
|
Family
ID: |
1000004964643 |
Appl.
No.: |
16/490,909 |
Filed: |
March 1, 2018 |
PCT
Filed: |
March 01, 2018 |
PCT No.: |
PCT/JP2018/007874 |
371(c)(1),(2),(4) Date: |
September 04, 2019 |
PCT
Pub. No.: |
WO2018/163973 |
PCT
Pub. Date: |
September 13, 2018 |
Prior Publication Data
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|
|
|
Document
Identifier |
Publication Date |
|
US 20200012134 A1 |
Jan 9, 2020 |
|
Foreign Application Priority Data
|
|
|
|
|
Mar 7, 2017 [JP] |
|
|
2017-042807 |
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G02F
1/13338 (20130101); G06F 3/0412 (20130101); G02F
1/133514 (20130101); G06F 3/0445 (20190501); G02F
1/133512 (20130101); G02F 1/13394 (20130101); G02F
2001/13398 (20130101); G02F 2201/123 (20130101); G06F
2203/04108 (20130101) |
Current International
Class: |
G02F
1/1333 (20060101); G06F 3/041 (20060101); G02F
1/1339 (20060101); G06F 3/044 (20060101); G02F
1/1335 (20060101) |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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|
|
|
|
|
|
2013-131110 |
|
Jul 2013 |
|
JP |
|
2014-164770 |
|
Sep 2014 |
|
JP |
|
2014-186711 |
|
Oct 2014 |
|
JP |
|
5871111 |
|
Mar 2016 |
|
JP |
|
2016-170730 |
|
Sep 2016 |
|
JP |
|
2016-224808 |
|
Dec 2016 |
|
JP |
|
Other References
Maruyama et al.; "Touch Panel and Electronic Device"; U.S. Appl.
No. 16/490,911, filed Sep. 4, 2019. cited by applicant.
|
Primary Examiner: Briggs; Nathanael R
Attorney, Agent or Firm: Keating & Bennett, LLP
Claims
The invention claimed is:
1. A touch panel having a display surface, comprising: a pixel
substrate, a liquid crystal layer, and a color filter layer in
order from a side farthest from the display surface, where a
direction from the pixel substrate toward the color filter layer is
defined as an upper direction and a direction opposite to the upper
direction is defined as a lower direction; a touch panel upper side
electrode layer located above the color filter layer; a touch panel
lower side electrode layer located below the color filter layer and
above the liquid crystal layer; a first conductive layer as a pixel
electrode layer located above the pixel substrate and below the
liquid crystal layer; and a piezoelectric element layer that
generates a voltage in accordance with a pressing on the display
surface, and wherein the touch panel upper side electrode layer and
the touch panel lower side electrode layer are provided with
electrodes for detecting a position at which an object contacts or
approaches the display surface, the piezoelectric element layer is
located between the touch panel lower side electrode layer and the
first conductive layer, a portion of the piezoelectric element
layer is provided within the liquid crystal layer, and the
piezoelectric element layer is a spacer that maintains a thickness
of the liquid crystal layer.
2. The touch panel according to claim 1, further comprising: a
light shielding member located above the piezoelectric element
layer, wherein the piezoelectric element layer is disposed at a
position covered with the light shielding member when viewed from
the upper side.
3. The touch panel according to claim 1, wherein a potential
difference between the touch panel lower side electrode layer and
the first conductive layer is acquired as a voltage for detecting
the pressing on the display surface.
4. An electronic device comprising the touch panel according to
claim 1.
5. A touch panel having a display surface, comprising: a pixel
substrate, a liquid crystal layer, and a color filter layer in
order from a side farthest from the display surface, where a
direction from the pixel substrate toward the color filter layer is
defined as an upper direction and a direction opposite to the upper
direction is defined as a lower direction; a touch panel upper side
electrode layer located above the color filter layer; a touch panel
lower side electrode layer located below the color filter layer and
above the liquid crystal layer; a first conductive layer as a pixel
electrode layer located above the pixel substrate and below the
liquid crystal layer; and a piezoelectric element layer that
generates a voltage in accordance with a pressing on the display
surface, wherein the touch panel upper side electrode layer and the
touch panel lower side electrode layer are provided with electrodes
for detecting a position at which an object contacts or approaches
the display surface, the piezoelectric element layer is located
between the touch panel lower side electrode layer and the first
conductive layer, the piezoelectric element layer is located below
the touch panel lower side electrode layer and above the liquid
crystal layer, the touch panel further comprises a second
conductive layer located below the piezoelectric element layer and
above the liquid crystal layer, and a potential difference between
the touch panel lower side electrode layer and the second
conductive layer is acquired as a voltage for detecting the
pressing on the display surface.
6. The touch panel according to claim 5, further comprising: a
light shielding member located above the piezoelectric element
layer, wherein the piezoelectric element layer is at a position
covered with the light shielding member when viewed from the upper
side.
7. The touch panel according to claim 5, wherein a potential
difference between the touch panel lower side electrode layer and
the first conductive layer is acquired as a voltage for detecting
the pressing on the display surface.
8. The touch panel according to claim 5, wherein a potential of the
second conductive layer is fixed.
9. An electronic device comprising the touch panel according to
claim 5.
Description
TECHNICAL FIELD
An aspect of the present invention relates to a touch panel having
both an input position detection function and a pressure detection
function.
BACKGROUND ART
In recent years, in some of touch panels (TP), a function for
detecting that pressure is applied to an input surface (display
surface) (hereinafter, pressure detection) has been added in
addition to the related input position detection function. Various
techniques have been proposed for a touch panel having both the
input position detection function and the pressure detection
function (hereinafter, also referred to as a pressure detection
type touch panel).
For example, PTL 1 discloses a technique for maintaining the
accuracy of pressure detection even when the touch panel is
miniaturized (with a reduced total number of films) in the pressure
detection type touch panel.
Specifically, the touch panel disclosed in PTL 1 includes a touch
panel unit provided with two touch panel electrodes (first touch
panel electrode and second touch panel electrode), and a pressure
sensor unit provided with two pressure sensor electrodes (first
pressure sensor electrode and a second pressure sensor
electrode).
Then, an electrode layer provided with the first pressure sensor
electrode (first pressure sensor electrode layer) is formed as the
same electrode layer as an electrode layer provided with the second
touch panel electrode (second touch panel electrode layer).
CITATION LIST
Patent Literature
PTL 1: Japanese Patent No. 5871111 (issued on Mar. 1, 2016)
SUMMARY OF INVENTION
Technical Problem
However, in the technique of PTL 1, the following two problems are
found, for example.
(1): The electrode layer provided with the second pressure sensor
electrode (second pressure sensor electrode layer) is not the same
electrode layer as any of the electrode layer provided with the
first touch panel electrode (first touch panel electrode layer) and
the second touch panel electrode layer described above. For this
reason, in order to provide the second pressure sensor electrode
layer, since an individual substrate (for example: film or glass)
and an adhesive layer are needed, the thickness of a touch panel is
increased.
(2): In addition, there is a possibility that unintended capacitive
coupling may occur between the second pressure sensor electrode
layer and other members. For this reason, there is a possibility
that noise of the touch panel may be increased due to the
capacitive coupling.
Thus, there is still room for improvement with regard to
miniaturization and performance improvement in the pressure
detection type touch panel. An aspect of the present invention is
to realize further miniaturization and performance improvement in
the pressure detection type touch panel.
Solution to Problem
In order to solve the problems, including to an aspect of the
present invention, there is provided a touch panel having a display
surface, including a pixel substrate, a liquid crystal layer, and a
color filter layer in order from a side farthest from the display
surface, in which when a direction from the pixel substrate toward
the color filter layer is defined as an upper direction and a
direction opposite to the upper direction is defined as a lower
direction, the touch panel further includes a touch panel upper
side electrode layer located above the color filter layer; a touch
panel lower side electrode layer located below the color filter
layer and above the liquid crystal layer; a first conductive layer
as a pixel electrode layer located above the pixel substrate and
below the liquid crystal layer; and a piezoelectric element layer
that generates a voltage in accordance with pressing on the display
surface, and in which the touch panel upper side electrode layer
and the touch panel lower side electrode layer are provided with
electrodes for detecting a position at which an object contacts or
approaches the display surface, and the piezoelectric element layer
is located between the touch panel lower side electrode layer and
the first conductive layer.
ADVANTAGEOUS EFFECTS OF INVENTION
According to a touch panel according to an aspect of the present
invention, there is an advantage that further miniaturization and
performance improvement can be achieved in the pressure detection
type touch panel.
BRIEF DESCRIPTION OF DRAWINGS
FIG. 1 is a view showing a schematic configuration of a display
device provided with a touch panel according to a first
embodiment.
(a) of FIG. 2 is a cross-sectional view viewed from a direction of
arrows A-A of FIG. 1, and (b) of FIG. 2 is a cross-sectional view
viewed from a direction of arrows B-B of FIG. 1.
FIG. 3 is a view for explaining the function of a piezoelectric
element layer.
FIG. 4 is a view for explaining a pressure detection voltage
obtained in the touch panel of FIG. 1.
FIG. 5 is a cross-sectional view showing a configuration of a touch
panel according to a second embodiment.
FIG. 6 is a cross-sectional view showing a configuration of a touch
panel according to a third embodiment.
FIG. 7 is a cross-sectional view showing a configuration of a touch
panel according to a fourth embodiment.
FIG. 8 is a view for explaining a pressure detection voltage
obtained in the touch panel according to the fourth embodiment.
DESCRIPTION OF EMBODIMENTS
First Embodiment
Hereinafter, the first embodiment will be described in detail with
reference to FIGS. 1 to 4. FIG. 1 is a view showing a schematic
configuration of a display device 100 (electronic device) provided
with a touch panel 1 according to the first embodiment. First, an
overview of the display device 100 will be described with reference
to FIG. 1. The display device 100 is an example of an electronic
device provided with a touch panel according to one embodiment of
the present invention.
However, the electronic device provided with the touch panel
(example: touch panel 1) according to one embodiment of the present
invention is not limited to the display device. The electronic
device may be a portable terminal such as a smartphone or a tablet,
for example. Alternatively, the electronic device may be an
information processing device such as a PC monitor, signage, an
electronic blackboard, or an information display.
In addition, although various members of the touch panel 1 are
shown in the drawings (in particular, FIG. 2 and the like) to be
described below, descriptions of the members not related to the
first embodiment will be omitted. It may be understood that these
members with descriptions omitted are similar to well-known ones.
It is to be noted that drawings are intended to provide an overview
of the shape, structure, and positional relationship of members,
and are not always drawn to scale.
(Overview of Display Device 100)
As shown in FIG. 1, the display device 100 includes a touch panel
1, a display unit 90 (display surface), a driver 91, a control
substrate 92, and a flexible printed circuit substrate (FPC) 93. In
addition, the touch panel 1 includes a thin film transistor (TFT)
substrate 11, a color filter (CF) substrate 18, and a display unit
90 (see also FIG. 2 and the like described below).
The display unit 90 may be a liquid crystal (LC) panel, for
example. The display unit 90 displays various images. Since the
display device 100 is provided with the touch panel 1, the display
unit 90 also serves as an input unit (input surface) that receives
an input operation of the user (for example, a touch input by the
finger F of the user). The display unit 90 may be referred to as an
active area.
The driver 91 serves as a display control unit that controls the
display unit 90. For example, the driver 91 may apply an
instruction to the TFT substrate 11 and control lighting of the
pixels (not shown) formed on the TFT substrate 11.
The control substrate 92 is a substrate provided with a main
control unit that collectively controls the operation of the
display device 100. A touch panel controller (not shown) that
controls the operation of the touch panel 1 may be provided on the
control substrate 92. Alternatively, the main control unit
described above may have the function of the touch panel
controller.
The FPC 93 is a member that connects the control substrate 92 and
the driver 91. The FPC 93 has high flexibility and may be highly
deformable. Therefore, the FPC 93 is suitable for manufacturing a
small or thin electronic device (for example, a portable
terminal).
In FIG. 1, a direction parallel to the short side of the display
device 100 (in other words, the short side of the display unit 90)
is referred to as the X direction. In addition, a direction
parallel to the long side of the display device 100 (long side of
the display unit 90) is referred to as the Y direction. In FIG. 1,
the X direction and the Y direction are orthogonal to each
other.
Further, in FIG. 1, a direction perpendicular to the paper surface
(that is, a direction perpendicular to the X direction and the Y
direction) is referred to as the Z direction. It is assumed that a
direction from the TFT substrate 11 toward the display unit 90
(that is, the side of the user (viewer) who views the image
displayed on the display unit 90) is a positive direction in the Z
direction. Hereinafter, the positive direction in the Z direction
is also referred to as the upper direction. The upper direction may
also be defined as a direction from the TFT substrate 11 toward the
CF substrate 18 in FIG. 2 described below.
Meanwhile, the negative direction in the Z direction (a direction
opposite to the upper direction) is also referred to as the lower
direction. Hereinafter, for convenience of description, the Z
direction is also referred to as the vertical direction. Further,
the upper side in the vertical direction is also referred to as a
viewer side.
(Touch Panel 1)
Subsequently, the touch panel 1 will be described with reference to
FIG. 2. FIG. 2 is a cross-sectional view showing the configuration
of the touch panel 1. Specifically, in (a) of FIG. 2 is a
cross-sectional view viewed from a direction of arrows A-A of FIG.
1, and FIG. (b) is a cross-sectional view viewed from a direction
of arrows B-B of FIG. 1. That is, in (a) of FIG. 2. (a) is a
cross-sectional view in the XZ plane of FIG. 1, and FIG. (b) is a
cross-sectional view in the YZ plane of FIG. 1.
In the touch panel 1, an electrode layer (a TP lower side electrode
layer 16 and a TP upper side electrode layer 19) for realizing an
input position detection function is formed on a lower side (inner)
than the display unit 90 when viewed from the upper side (viewer
side). From this, the touch panel 1 is also referred to as an
in-cell type touch panel.
As shown in (a) of FIG. 2, the touch panel 1 includes, from the
lower side toward the upper side (that is, in order of distance
from the display unit 90), a TFT substrate 11 (pixel substrate), an
insulating layer 12, and an indium tin oxide (ITO) layer 13, a
liquid crystal layer 14, a piezoelectric element layer 15, a TP
lower side electrode layer 16 (touch panel lower side electrode
layer), a black matrix (BM) 17, a CF substrate 18 (color filter
layer), and a TP upper side electrode layer 19 (touch panel upper
side electrode layer) in this order. In addition, on the upper side
of the TP upper side electrode layer 19, a display unit 90 (not
shown except for FIG. 1) is further provided.
In the inside of the liquid crystal layer 14, a photo spacer (PS)
140 is provided. The PS 140 is a member (spacer) for maintaining a
uniform thickness (length in the Z direction) of the liquid crystal
layer 14. The PS 140 may be formed in a columnar shape.
As shown in (b) of FIG. 2, in the touch panel 1, a planarization
layer 115 may be provided above the TFT substrate 11 and below the
insulating layer 12.
On the TFT substrate 11, (i) a plurality of pixels of red, green,
blue (RGB) (that is, pixels forming an image displayed on the
display unit 90), and (ii) TFTs corresponding to the respective
pixels are spatially regularly arranged. The TFT serves as a
switching element that controls the lighting of the pixels. The
light emitted from each pixel is directed upward. In FIG. 2 and the
like, the pixels and the TFTs are not illustrated for
simplification.
In the ITO layer 13 (first conductive layer, pixel electrode
layer), a pixel electrode (not shown) for driving the pixels in the
TFT substrate 11 is formed. The ITO layer 13 is a transparent layer
because ITO is a material that is particularly excellent in
light-transmitting. Therefore, the ITO layer 13 does not hinder the
viewability of the user who views the image displayed on the
display unit 90. The insulating layer 12 is provided to protect
various wirings of the TFT substrate 11 and the ITO layer 13.
The liquid crystal layer 14 contains a liquid crystal material of
which coordination is changed according to the voltage applied to
the liquid crystal layer 14. Therefore, the light transmittance of
the liquid crystal layer 14 may be adjusted according to the
voltage applied to the liquid crystal layer 14.
The piezoelectric element layer 15 is a layer formed of a
piezoelectric material. The piezoelectric element layer 15 serves
as a piezoelectric element (also referred to as a piezoelectric
element). The piezoelectric element layer 15 is formed on an upper
surface of the liquid crystal layer 14. That is, the piezoelectric
element layer 15 is located below the TP lower side electrode layer
16 described below. The piezoelectric element layer 15 also serves
as a planarization layer on the upper surface of the liquid crystal
layer 14. Alternatively, as described in the second embodiment to
be described below, a planarization layer 155 may be provided on at
least a portion of the upper surface of the liquid crystal layer 14
(see FIG. 5 described below).
The TP lower side electrode layer 16 is a layer, within which one
of a drive electrode (also referred to as a drive line) or a sense
electrode (also referred to as a sense line) is formed. The first
embodiment exemplifies a case in which the TP lower side electrode
layer 16 is a drive electrode layer within which a drive electrode
is formed. The TP lower side electrode layer 16 is formed on an
upper surface of the piezoelectric element layer 15. In addition,
the TP lower side electrode layer 16 is located below the CF
substrate 18. In FIG. 2 and the like, the drive electrodes and the
sense electrodes are not illustrated for simplification.
The material of the drive electrode (in other words, the material
of the TP lower side electrode layer 16) is not particularly
limited. The first embodiment exemplifies a case in which the
material of the drive electrode is Cu (copper). In addition, since
Cu is a non-transparent material, it is desirable that the drive
electrode be formed so as not to hinder the viewability of the
user. For example, the drive electrode may be formed in a metal
mesh shape. Alternatively, a transparent conductive material (for
example, ITO) may be used for the drive electrode from the
viewpoint of improving the viewability of the user.
The BM 17 (light shielding member) is a light shielding member
disposed so as to surround the neighbor of each pixel described
above when viewed from the upper direction. The outline of each
pixel is emphasized by partitioning each pixel with the BM 17.
Therefore, the contrast of the image displayed on the display unit
90 is improved.
The CF substrate 18 is a substrate provided with a color filter
that transmits light in a certain wavelength range. For example,
the CF substrate 18 may include three types of color filters: (i) a
first color filter that transmits red (R) light, (ii) a second
color filter that transmits green (G) light, and (iii) a third
color filter that transmits blue (B) light. On the CF substrate 18,
a plurality of color filters are spatially regularly arranged. In
FIG. 2 and the like, the corresponding color filter is not
illustrated for the simplification of drawing.
The TP upper side electrode layer 19 is a layer having one of the
drive electrode or the sense electrode formed therewithin, which is
a different type of electrode from the electrode (for example, the
drive electrode) formed on the TP lower side electrode layer 16.
The first embodiment exemplifies the case in which the TP upper
side electrode layer 19 is the sense electrode layer within which a
sense electrode is formed. The TP upper side electrode layer 19 is
formed on an upper surface of the CF substrate 18.
The material of the sense electrode (in other words, the material
of the TP upper side electrode layer 19) is not particularly
limited, as in the case of the material of the drive electrode
described above. The first embodiment exemplifies the case in which
the material of the sense electrode is ITO. Alternatively, a
non-transparent material (for example, Cu) may also be used as the
material of the sense electrode.
The drive electrode and the sense electrode are electrodes for
detecting a position where an object (for example, the finger F in
FIG. 1 described above) contacts or approaches the display unit 90.
In the first embodiment, a plurality of drive electrodes are
arranged along the X direction, for example. In addition, a
plurality of sense electrodes are arranged along the Y direction,
for example.
The touch panel 1 may detect a value (signal value) of the
capacitance formed at the intersection of each of the plurality of
drive electrodes and each of the plurality of sense electrodes.
Then, based on the signal value, the touch panel 1 may detect (i)
contact or proximity of an object to the display unit 90, and (ii)
a position on the display unit 90 at which the contact or approach
occurs. That is, the touch panel 1 may be a capacitive touch
panel.
The TP lower side electrode layer 16 and the TP upper side
electrode layer 19 (in other words, the drive electrode and the
sense electrode) are connected to the touch panel controller
described above with wirings (not shown). The drive electrode and
the sense electrode are each driven by a touch panel controller.
The operation of the touch panel controller for performing the
signal value detection and the input position detection is
well-known and thus the description thereof is not repeated.
As described above, the touch panel 1 is provided with the TP upper
side electrode layer 19 and the TP lower side electrode layer 16,
so that the position on the display unit 90 where the touch input
is performed with the finger F, for example, may be detected.
As described above, the first embodiment exemplifies the case in
which the TP lower side electrode layer 16 is the drive electrode
layer and the TP upper side electrode layer 19 is the sense
electrode layer. Alternatively, the TP lower side electrode layer
16 may be provided as the sense electrode layer, and the TP upper
side electrode layer 19 may be provided as the drive electrode
layer.
(Function of Piezoelectric Element Layer 15)
FIG. 3 is a diagram for explaining the function of the
piezoelectric element layer 15 (piezoelectric element). As shown in
FIG. 3, it is assumed that the upper side electrode layer 151U is
provided on an upper surface of the piezoelectric element layer 15
and the lower side electrode layer 151L is provided on a lower
surface of the piezoelectric element layer 15. The upper side
electrode layer 151U and the lower side electrode layer 151L are
layers in which electrodes are formed for detecting a voltage
generated in the piezoelectric element layer 15 (that is, a
potential difference between the upper side electrode layer 151U
and the lower side electrode layer 151L).
The piezoelectric element is an element that generates polarization
charge on the surface in accordance with pressure (distortion) when
the pressure is applied to the element itself (more strictly
speaking, when distortion is generated in the element itself). That
is, the piezoelectric element generates a potential difference
(voltage) in accordance with the pressure between a pressing
surface and a surface opposed to the pressing surface. More
specifically, as the pressure applied to the piezoelectric element
increases, the voltage generated in the piezoelectric element also
increases.
As an example, as shown with the legend "unpressed" in FIG. 3, when
the upper side electrode layer 151U is not pressed, the
piezoelectric element layer 15 is not pressed as well. Therefore,
the piezoelectric element layer 15 does not generate a voltage.
Meanwhile, as shown with the legend "pressed" in FIG. 3, when the
upper side electrode layer 151U is pressed by the finger F of the
user, for example, the piezoelectric element layer 15 is also
pressed. Therefore, the piezoelectric element layer 15 generates a
voltage.
Hereinafter, in the touch panel 1, a voltage for detecting a
pressing on the display unit 90 is referred to as a voltage VP. The
voltage VP may be referred to as a pressure detection voltage. In
the configuration of FIG. 3, when the piezoelectric element layer
15 is pressed, the voltage generated in the piezoelectric element
layer 15 may be acquired as a voltage VP (the pressure detection
voltage).
FIG. 4 is a view for explaining the voltage VP (the pressure
detection voltage) obtained in the touch panel 1. As described
above, in the touch panel 1, the piezoelectric element layer 15 is
located between the TP lower side electrode layer 16 and the ITO
layer 13. Therefore, in the touch panel 1, the TP lower side
electrode layer 16 may play the role of the upper side electrode
layer 151U, and the ITO layer 13 may play the role of the lower
side electrode layer 151L, respectively.
That is, in the touch panel 1, the potential difference between the
TP lower side electrode layer 16 and the ITO layer 13 may be
acquired as the voltage VP (the pressure detection voltage)
described above. Note that, for the sake of distinguishing from the
voltage VP in FIG. 3, the voltage VP in FIG. 4 (the potential
difference between the TP lower side electrode layer 16 and the ITO
layer 13) is also referred to as a voltage VP1. In the touch panel
1, a voltage is generated in the piezoelectric element layer 15 by
the piezoelectric element layer 15 being pressed in accordance with
the pressing of the display unit 90.
In the touch panel 1, at least one of the TP lower side electrode
layer 16 and the ITO layer 13 is connected to the touch panel
controller by wirings (not shown). The touch panel controller
performs a processing (pressure detection processing) of detecting
whether or not the display unit 90 is pressed based on the voltage
VP1 acquired through the wirings. Since the pressure detection
processing is well-known, the description is skipped.
Note that the material of the piezoelectric element layer 15 is not
particularly limited. For example, as a material of the
piezoelectric element layer 15, polyvinylidene fluoride (PVDF),
poly L-lactide (PLLA), and the like may be used.
Meanwhile, since the piezoelectric element layer 15 is a member
provided on the touch panel 1 (in-cell type touch panel) including
the display unit 90, it is desirable that it does not hinder the
viewability of the user. Therefore, for a material of the
piezoelectric element layer 15, for example, it is desirable to
select a material excellent in light transmittance.
Further, in consideration of the color of members in a neighbor of
the piezoelectric element layer 15 in the touch panel 1, it is
desirable to select a material having a color close to that of the
members in the neighbor as the material of the piezoelectric
element layer 15.
In addition, as the material of the piezoelectric element layer 15,
it is desirable to select a material which does not cause the phase
difference (retardation) of light as much as possible so that the
phase of light emitted from the upper surface of the piezoelectric
element layer 15 does not greatly differ from the phase of light
incident on the lower surface of the piezoelectric element layer
15.
From the viewpoint of further reducing the phase difference of
light, a phase difference film may be provided above the
piezoelectric element layer 15. This is because even when a phase
difference of light occurs in the piezoelectric element layer 15,
the phase difference film may compensate (lessen) the phase
difference.
(Effect of Touch Panel 1)
As described above, in the touch panel 1, the input position
detection function of the touch panel 1 is realized with the TP
upper side electrode layer 19 and the TP lower side electrode layer
16. In addition, the TP lower side electrode layer 16 and the ITO
layer 13 are provided so as to sandwich the piezoelectric element
layer 15 therebetween.
Therefore, as shown in FIG. 4 described above, the TP lower side
electrode layer 16 and the ITO layer 13 may be used as the
electrode layers (electrodes) for acquiring the voltage VP1
(pressure detection voltage). Therefore, the pressure detection
function of the touch panel 1 is realized by the piezoelectric
element layer 15 located between the TP lower side electrode layer
16 and the ITO layer 13.
As described above, according to the touch panel 1, a pressure
detection type touch panel (a touch panel having both input
position detection function and pressure detection function) can be
configured without requiring the second pressure sensor electrode
layer that was present in the touch panel of PTL 1 described above.
The main advantages of the touch panel 1 obtained by this
configuration are as follows in (1) and (2).
(1): In the touch panel of PTL 1, since a separate substrate and an
adhesive layer are employed to provide the second pressure sensor
electrode layer, the thickness of the touch panel is increased. On
the other hand, according to the configuration of the touch panel
1, since the second pressure sensor electrode layer is not present,
the substrate and adhesive layer described above may not be
employed.
As described above, in the touch panel 1, compared to the touch
panel described in PTL 1, an increase in the thickness of the touch
panel may be suppressed, so that it is possible to realize further
miniaturization of the touch panel.
(2): In the touch panel 1, the second pressure sensor electrode
layer is not present. For this reason, there is no capacitive
coupling (capacitive coupling unintended in design, which is
present in the touch panel of PTL 1) caused by the second pressure
sensor electrode layer.
Therefore, compared with the touch panel of PTL 1, the touch panel
1 can suppress unintended capacitive coupling in design. Therefore,
an increase in noise of the touch panel due to the capacitive
coupling can be suppressed, so that it possible to further improve
the performance of the touch panel (for example, the performance of
at least one of the position detection function and the pressure
detection function).
As described above, according to the touch panel 1, it is possible
to realize further miniaturization and performance improvement in
the pressure detection type touch panel (a touch panel having both
the input position detection function and the pressure detection
function).
(Supplemental Note)
As shown in FIG. 4 described above, according to the arrangement of
the piezoelectric element layer 15 in the touch panel 1, the
voltage VP1 (pressure detection voltage) may be acquired using the
TP lower side electrode layer 16 and the ITO layer 13.
That is, in the touch panel 1, two electrode layers (upper side
electrode layer and lower side electrode layer sandwiching the
piezoelectric element layer 15 therebetween) for detecting the
pressure detection voltage are both provided below the CF substrate
18. Therefore, the viewability of the user can be improved as
compared with the case in which the upper side electrode layer is
provided above the CF substrate 18, for example.
Further, in the touch panel 1, the two electrode layers may be
provided only in the vicinity of the liquid crystal layer 14, so
that the manufacturing process of the touch panel 1 can be
simplified. As a result, the manufacturing cost of the touch panel
1 can also be reduced.
Modification Example
In the first embodiment, for convenience of explanation, the
configuration in which the TP upper side electrode layer 19 is
located on the upper surface of the CF substrate 18 has been
exemplified. It is to be noted that the TP upper side electrode
layer 19 does not need to be in direct contact with the upper
surface of the CF substrate 18, and may be in indirect contact with
the upper surface of the CF substrate 18 through a certain member
(for example, an additional layer). The TP upper side electrode
layer 19 may be disposed above the CF substrate 18.
Further, in the first embodiment, the configuration in which the TP
lower side electrode layer 16 is located on the upper surface of
the piezoelectric element layer 15 has been exemplified.
Alternatively, the TP lower side electrode layer 16 also does not
need to be in direct contact with the upper surface of the
piezoelectric element layer 15, and may be in indirect contact with
the upper surface of the piezoelectric element layer 15 through a
certain member (for example, additional layer). The TP lower side
electrode layer 16 may be located below the CF substrate 18 and
above the piezoelectric element layer 15.
The same applies to each of the members except the TP upper side
electrode layer 19 and the TP lower side electrode layer 16.
Second Embodiment
Hereinafter, the second embodiment will be described with reference
to FIG. 5. It is to be noted that, for convenience of explanation,
parts having the same function as the parts described in the
embodiment described above are denoted by the same reference
numerals, and description thereof will not be repeated.
FIG. 5 is a cross-sectional view showing the configuration of the
touch panel 2 according to the second embodiment. Specifically,
FIG. 5 shows a cross-sectional view viewed from a direction of
arrows B-B in FIG. 1 described above. In the following embodiments,
for convenience of explanation, the cross-sectional view viewed
from a direction of arrows A-A in FIG. 1 will be skipped.
The touch panel 2 has a configuration in which the piezoelectric
element layer 15 is replaced with a piezoelectric element layer 25
in the touch panel 1 according to the first embodiment. The
piezoelectric element layer 25 is the same as the piezoelectric
element layer 15 of the first embodiment in that it is disposed so
as to be sandwiched between the TP lower side electrode layer 16
and the ITO layer 13.
Alternatively, the piezoelectric element layer 25 is disposed so as
to be covered by a lower surface of the BM 17. That is, when viewed
from the upper side, the piezoelectric element layer 25 is provided
so as to be blocked by the BM 17 and not visually recognized by the
user. In other words, when viewed in the Z direction (the normal
line direction of the piezoelectric element layer 25), the
piezoelectric element layer 25 is disposed so as to overlap the BM
17 as much as possible. Regarding this point, the piezoelectric
element layer 25 is different from the piezoelectric element layer
15.
Note that, in the touch panel 2, the planarization layer 155 may be
provided on a portion of the upper surface of the liquid crystal
layer 14. In the touch panel 2, the planarization layer 155 is
provided so as to fill a portion in the touch panel 1 where the
piezoelectric element layer 15 was present and where the
piezoelectric element layer 25 is not present.
As an example, the piezoelectric element layer 25 may be formed by
patterning only a portion of the lower surface of the TP lower side
electrode layer 16. Note that the thickness of the piezoelectric
element layer 25 may be equal to the thickness of the TP lower side
electrode layer 16 or may be different from the thickness of the TP
lower side electrode layer 16. The piezoelectric element layer 25
may be formed thicker than the TP lower side electrode layer 16 or
may be formed thinner than the TP lower side electrode layer
16.
According to the arrangement of the piezoelectric element layer 25,
when viewed from the upper side, the piezoelectric element layer 25
may be covered and hidden by the BM 17. Therefore, it is possible
to prevent the viewability of the user from being hindered by the
piezoelectric element layer 25. That is, according to the touch
panel 2, compared with the touch panel 1, it is possible to further
improve the viewability of the user.
Third Embodiment
Hereinafter, the third embodiment will be described with reference
to FIG. 6. FIG. 6 is a cross-sectional view showing the
configuration of the touch panel 3 according to the third
embodiment. Specifically, FIG. 6 shows a cross-sectional view
viewed from a direction of arrows B-B in FIG. 1 described
above.
As shown in FIG. 6, the touch panel 3 has a configuration in which,
in the touch panel 2 according to the second embodiment, (i) the
piezoelectric element layer 25 is removed and (ii) the PS 140 is
replaced with the piezoelectric element layer 350. As described
below, the piezoelectric element layer 350 serves as both the
piezoelectric element layer 25 and the PS 140.
The piezoelectric element layer 350 is the same as the
piezoelectric element layer 25 (or the piezoelectric element layer
15) in view of the function of the piezoelectric element itself. In
the touch panel 3, the piezoelectric element layer 350 is pressed
in accordance with the pressing on the display unit 90. Therefore,
the piezoelectric element layer 350 generates a voltage in
accordance with the pressure applied thereto.
In addition, the piezoelectric element layer 350 also has a
function as the PS 140 (function as a spacer). The piezoelectric
element layer 350 is formed in the same size and shape (columnar
shape) as the PS 140. As shown in FIG. 6, a portion of the
piezoelectric element layer 350 is provided within the liquid
crystal layer 14.
Hereinafter, in the piezoelectric element layer 350, a portion
provided within the liquid crystal layer 14 is also referred to as
a spacer portion. The piezoelectric element layer 350 is formed to
be sufficiently thicker than the piezoelectric element layer 25 of
the second embodiment (or the piezoelectric element layer 15 of the
first embodiment) in order to maintain a uniform thickness of the
liquid crystal layer 14 with the spacer portion.
Alternatively, the entire piezoelectric element layer 350 may be
provided within the liquid crystal layer 14. That is, the entire
piezoelectric element layer 350 may be used as the spacer portion.
As described above, the piezoelectric element layer 350 may be
formed to have a spacer portion (so that at least a portion of the
piezoelectric element layer 350 is provided within the liquid
crystal layer 14).
The piezoelectric element layer 350 serves as a spacer, so that
relatively large pressure is applied to the upper surface of the
piezoelectric element layer 350 when the display unit 90 is
pressed. Therefore, when the display unit 90 is pressed, a voltage
may be generated in the piezoelectric element layer 350.
Further, the piezoelectric element layer 350 serves as a spacer, so
that an increase in the thickness of the touch panel 3 can be
suppressed even when the piezoelectric element layer 350 which is
thicker than the piezoelectric element layer 25 is provided.
Therefore, the configuration of the piezoelectric element layer 350
is also desirable from the viewpoint of miniaturization of the
touch panel 3. In addition, since some of the plurality of PSs 140
provided on the touch panel 2 can be replaced with the
piezoelectric element layer 350, the number of parts of the touch
panel 3 can be reduced by providing the piezoelectric element layer
350.
As shown in FIG. 6, the piezoelectric element layer 350 is provided
at the same position as the PS 140. That is, like the piezoelectric
element layer 25, the piezoelectric element layer 350 is also
disposed so as to be covered by the lower surface of the BM 17. As
described above, the piezoelectric element layer 350 is also
disposed so as to overlap the BM 17 when viewed in the Z direction
(the normal line direction of the piezoelectric element layer
350).
By arranging the piezoelectric element layer 350 in this manner,
when viewed from the upper side, the piezoelectric element layer
350 is, like the piezoelectric element layer 25, also blocked by
the BM 17 and not visually recognized by the user. Therefore, even
when the piezoelectric element layer 350 which is thicker than the
piezoelectric element layer 25 is provided, the viewability of the
user can be enhanced as in the touch panel 2.
Alternatively, that is, the piezoelectric element layer 350 may not
be disposed so as to be covered and hidden by the BM 17 when viewed
from the upper side. For example, in the touch panel 1 according to
the first embodiment, the touch panel 3 may be configured by (i)
removing the piezoelectric element layer 15 and (ii) replacing the
PS 140 with the piezoelectric element layer 350.
Fourth Embodiment
Hereinafter, the fourth embodiment will be described with reference
to FIGS. 7 and 8. FIG. 7 is a cross-sectional view showing the
configuration of the touch panel 4 according to the fourth
embodiment. Specifically, specifically, FIG. 7 shows a
cross-sectional view viewed from a direction of arrows B-B in FIG.
1 described above.
The touch panel 4 has a configuration in which the conductive layer
410 (the second conductive layer) is added to the touch panel 1
according to the first embodiment. Alternatively, the touch panel 4
may be configured by adding the conductive layer 410 to the touch
panel 2 according to the second embodiment.
The conductive layer 410 is provided below the piezoelectric
element layer 15 (piezoelectric element layer located below the TP
lower side electrode layer 16 and above the liquid crystal layer
14) and above the liquid crystal layer 14. As an example, the
conductive layer 410 may be formed on the lower surface of the
piezoelectric element layer 15. The conductive layer 410 may be
formed of ITO (the same material as the ITO layer 13 which is a
first conductive layer (pixel electrode layer)) in order to improve
the viewability of the user, for example. Alternatively, as the
material of the conductive layer 410, a non-transparent material
may be used.
FIG. 8 is a view for explaining the voltage VP (the pressure
detection voltage) obtained in the touch panel 4. In the touch
panel 4, the TP lower side electrode layer 16 and the conductive
layer 410 are located to sandwich the piezoelectric element layer
15 therebetween.
That is, in the touch panel 4, instead of the ITO layer 13, the
conductive layer 410 plays a role of the lower side electrode layer
151L (see FIG. 3 described above). Regarding this point, the touch
panel 4 is different from the touch panel 1.
For this reason, in the touch panel 4, the potential difference
between the TP lower side electrode layer 16 and the conductive
layer 410 may be acquired as the voltage VP. Hereinafter, for being
distinguished from the voltage VP1 in the first embodiment, the
voltage VP (the potential difference between the TP lower side
electrode layer 16 and the conductive layer 410) in FIG. 8 is also
referred to as a voltage VP2.
(Possible Improvements in Touch Panel 1)
Here, prior to the description of the effects of the touch panel 4,
the touch panel 1 according to the first embodiment will be
described again. In the touch panel 1, in order to detect (acquire)
the voltage VP (pressure detection voltage) with high accuracy, it
is desirable to fix the potential of one of the two electrode
layers (upper side electrode layer and lower side electrode layer
sandwiching the piezoelectric element layer 15 therebetween) for
detecting the voltage VP.
Meanwhile, the TP lower side electrode layer 16 (upper side
electrode layer) is an electrode layer for realizing the input
position detection function of the touch panel 1, and in the state
where the pressure (stress) is not applied to the display unit 90,
the potential thereof is calibrated in advance. Therefore, in terms
of maintaining the input position detection performance of the
touch panel 1, it is not desirable to fix the potential of the TP
lower side electrode layer 16.
Therefore, in order to improve the accuracy of the voltage VP, it
is conceivable to fix the potential of the ITO layer 13 (lower side
electrode layer). As an example, it is conceivable that the
potential of the ITO layer 13 is fixed (for example, the ITO layer
13 is connected to a constant voltage source (not shown)) during a
certain time (hereinafter, pressure detection time) in which the
pressure detection processing is performed.
On the other hand, the ITO layer 13 is a pixel electrode layer that
drives the pixels. Therefore, when the potential of the ITO layer
13 is fixed, the pixel may not be driven by the ITO layer 13 (more
specifically, the pixel electrode formed in the ITO layer 13) in
the pressure detection time. That is, the degree of freedom in
driving the pixels by the ITO layer 13 is reduced.
That is, in the touch panel 1, when the potential of the ITO layer
13 (lower side electrode layer) is fixed (when the accuracy of the
voltage VP is improved), the pressure detection processing and the
driving of the pixel may not be performed independently
(simultaneously). Regarding this point, it can be said that the
touch panel 1 has room for improvement.
(Effect of Touch Panel 4)
In the touch panel 4, in order to improve the accuracy of the
voltage VP, the potential of the conductive layer 410 (lower side
electrode layer) may be fixed instead of fixing the potential of
the ITO layer 13 (pixel electrode layer). For example, the
conductive layer 410 may be connected to a ground terminal (not
illustrated) to fix the potential of the conductive layer 410.
Since the conductive layer 410 in the touch panel 4 is an electrode
layer different from the ITO layer 13, even when the potential of
the conductive layer 410 is fixed, driving of pixels by the ITO
layer 13 is not affected. As described above, in the touch panel 4,
the accuracy of the voltage VP can be improved without fixing the
potential of the ITO layer 13.
Therefore, even when the touch panel 4 improves the accuracy of the
voltage VP, the pressure detection processing and the driving of
the pixel may be performed independently. That is, it is possible
to improve the pressure detection performance while maintaining the
input position detection performance and the image display
performance of the touch panel 4.
As described above, according to the touch panel 4, it is possible
to obtain the pressure detection voltage (voltage VP 2) with higher
accuracy than the pressure detection voltage (voltage VP1) in the
touch panel 1. As a result, the accuracy of pressure detection can
be enhanced.
CONCLUSION
The touch panel 1 according to a first aspect of the present
invention is a touch panel including a display surface (display
unit 90), which further includes a touch panel upper side electrode
layer (TP upper side electrode layer 19) including a pixel
substrate (TFT substrate 11), a liquid crystal layer (14), and a
color filter layer (CF substrate 18) in order of distance from the
display surface, and located above the color filter layer, with a
direction from the pixel substrate toward the color filter layer
being an upper direction and a direction opposite to the upper
direction being a lower direction, a touch panel lower side
electrode layer located below the color filter layer and above the
liquid crystal layer (TP lower side electrode layer 16), a first
conductive layer (ITO layer 13) as a pixel electrode layer located
above the pixel substrate and below the liquid crystal layer, and a
piezoelectric element layer 15 that generates a voltage in
accordance with a pressing on the display surface, in which the
touch panel upper side electrode layer and the touch panel lower
side electrode layer are provided with electrodes for detecting a
position at which an object contacts or approaches the display
surface, and the piezoelectric element layer is located between the
touch panel lower side electrode layer and the first conductive
layer.
With this configuration, the input position detection function of
the touch panel can be realized by the touch panel upper side
electrode layer and the touch panel lower side electrode layer. In
addition, the pressure detection function of the touch panel can be
realized by the piezoelectric element layer located between the
touch panel lower side electrode layer and the first conductive
layer.
Therefore, a pressure detection type touch panel (a touch panel
having both input position detection function and pressure
detection function) can be configured without employing the second
pressure sensor electrode layer that was present in the touch panel
of PTL 1 described above.
As a result, as described above, (i) the increase in the thickness
of the touch panel due to the presence of the second pressure
sensor electrode layer, and (ii) the increase in noise due to the
presence of the second pressure sensor electrode layer can both be
suppressed. Therefore, it is possible to implement further
miniaturization and performance improvement in the pressure
detection type touch panel.
In the touch panel according to the second aspect of the present
invention, it is desirable that, in the first aspect described
above, a light shielding member (17) located above the
piezoelectric element layer is further included, in which the
piezoelectric element layer is disposed in the position covered by
the light shielding member when viewed from the upper side.
With this configuration, when viewed from the upper side (for
example, when the user views an image displayed on the display
surface), the piezoelectric element layer can be covered and hidden
by the shielding member. Therefore, it is possible to improve the
viewability of the user.
In the touch panel according to the third aspect of the present
invention, it is desirable that, in the first or second aspect
described above, at least a portion of the piezoelectric element
layer (350) is provided within the liquid crystal layer, and the
piezoelectric element layer serves as a spacer for maintaining the
thickness of the liquid crystal layer.
With this configuration, the piezoelectric element layer can have
the function of the spacer. For this reason, since some of the
plurality of spacers (for example: PSs 140) provided in the touch
panel may be replaced with the piezoelectric element layer, it is
possible to reduce the number of parts of the touch panel. Further,
even when the piezoelectric element layer is thickly formed, the
increase in the thickness of the touch panel can be suppressed.
In the touch panel according to the fourth aspect of the present
invention, it is desirable that, a potential difference between the
touch panel lower side electrode layer and the first conductive
layer is acquired as a voltage (voltage VP1) for detecting the
pressing on the display surface.
As described above, in the touch panel according to an aspect of
the present invention, the touch panel lower side electrode layer
and the first conductive layer are provided to sandwich the
piezoelectric element layer therebetween. Therefore, as in the
above configuration, the touch panel lower side electrode layer and
the first conductive layer may be used as two electrode layers
(electrodes) for acquiring a voltage (potential difference
generated between the upper surface and the lower surface of the
piezoelectric element layer) generated in the piezoelectric element
layer in accordance with the pressing on the display surface.
According to the touch panel according to the fifth aspect of the
present invention, in the first or second aspect described above,
the piezoelectric element layer may be located below the touch
panel lower side electrode layer and above the liquid crystal layer
and may further include a second conductive layer (conductive layer
410) located below the piezoelectric element layer and above the
liquid crystal layer, and may acquire a potential difference
between the touch panel lower side electrode layer and the second
conductive layer as a voltage (voltage VP2) for detecting the
pressure on the display surface.
With this configuration, the piezoelectric element layer can be
sandwiched by the touch panel lower side electrode layer and the
second conductive layer. Therefore, as in the above configuration,
the touch panel lower side electrode layer and the second
conductive layer may also be used as two electrode layers for
acquiring a voltage generated in the piezoelectric element layer in
accordance with the pressing on the display surface.
According to the touch panel according to the sixth aspect of the
present invention, in the fifth aspect described above, it is
desirable that the potential of the second conductive layer is
fixed.
With this configuration, the voltage for detecting the pressure on
the display surface can be acquired in a state in which the
potential of the first conductive layer (pixel electrode layer) is
not fixed, but the potential (voltage VP, pressure detection
voltage) of the second conductive layer is fixed. Therefore, it is
possible to improve the pressure detection performance while
maintaining the image display performance of the touch panel.
According to the electronic device (display device 100) according
to the seventh aspect of the present invention, it is desirable
that the touch panel according to any one of the first to sixth
aspects described above is included.
With this configuration, the same effect as the touch panel
according to an aspect of the present invention is achieved.
Additional Note
An aspect of the present invention is not limited to the
embodiments described above, and various modifications may be
realized within the scope of the claims, and embodiments obtained
by appropriately combining the technical means disclosed in the
different embodiments are also included in the technical scope of
an aspect of the present invention. Furthermore, new technical
features may be formed by combining the technical means disclosed
in the embodiments.
REFERENCE SIGNS LIST
1, 2, 3, 4 touch panel
11 TFT substrate (pixel substrate)
13 ITO layer (first conductive layer, pixel electrode layer)
14 liquid crystal layer
15, 25, 350 piezoelectric element layer
16 TP lower side electrode layer (touch panel lower side electrode
layer)
17 BM (light shielding member)
18 CF substrate (color filter layer)
19 TP upper side electrode layer (touch panel upper side electrode
layer)
90 display unit (display surface)
100 display device (electronic device)
410 conductive layer (second conductive layer)
F finger (object)
VP voltage
VP1 voltage (potential difference between touch panel lower side
electrode layer and first conductive layer)
VP2 voltage (potential difference between touch panel lower side
electrode layer and second conductive layer)
* * * * *